Ultrasonic Waveform Deconvolution for Downhole Caliper Accuracy

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Solution Overview

Problem

Conventional ultrasonic caliper processing techniques are vulnerable to noise and struggle to accurately measure borehole size and configuration, particularly in the presence of multiple reflectors, and fail to provide quantitative information such as acoustic impedance for imaging.

Innovation Solution

The use of deconvolution techniques to process downhole ultrasonic waveforms, allowing for the derivation of two-way travel time and acoustic impedance by separating the source wavelet from the received waveforms, enabling robust calculation and amplitude preservation, which improves noise resilience and segregates multiple reflectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional cross-correlation processing is used with an a priori wavelet template, then the processing method is simple and straightforward, but the technique is very vulnerable to noise and has difficulty segregating between multiple reflectors

Engineering Contradiction:

Improveprocessing simplicityVSAvoidnoise resilience

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent extracts and removes the source wavelet component from the received waveform through deconvolution processing. By separating the source wavelet effect from the reflected waveform, the method isolates the true reflector information from noise contamination, enabling reliable detection even in noisy environments with multiple reflectors.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of correlating the received waveform with a template (conventional approach), the patent applies deconvolution - essentially inverting the convolution process that generated the received waveform. This inversion approach fundamentally changes the processing paradigm from template matching to source removal, improving noise resilience and reflector segregation.

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If conventional cross-correlation processing is used, then the processing method is straightforward, but the technique is not amplitude preserving and cannot provide quantitative information such as acoustic impedance

Engineering Contradiction:

Improveprocessing simplicityVSAvoidquantitative information

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The deconvolution process extracts the source wavelet component from the received waveform, preserving the amplitude information of the reflected waves. This extraction maintains the quantitative relationship between wave amplitudes and acoustic impedance, enabling calculation of formation properties that were lost in conventional processing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical cross-correlation operation with a deconvolution operation that preserves amplitude information. By substituting the processing mechanism from correlation-based to deconvolution-based, the system maintains quantitative amplitude relationships necessary for acoustic impedance calculation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the source waveform is localized with sufficient ring-down, then the reflected waveforms can be measured without source waveform contamination, but the technique remains vulnerable to noise from ring down waveform and tool body conduction

Engineering Contradiction:

Improvesource waveform localizationVSAvoidnoise from ring down and tool body

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the source wavelet component from the received waveform using deconvolution. This extraction eliminates residual source waveform contamination including ring-down effects and tool body conduction noise, allowing clean measurement of reflected waveforms even when source localization is imperfect.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful effect of source waveform contamination into a beneficial process. By deliberately modeling and removing the source wavelet through deconvolution, the method transforms what was previously a source of noise and contamination into a means of isolating and enhancing the true reflector signals.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables accurate calculation of borehole size and acoustic impedance, providing quantitative information for imaging and improving noise resilience, allowing for real-time operation and effective identification of multiple reflectors.

Implementation Method 1

transmitting an ultrasonic waveform, whereby the ultrasonic waveform is attenuated by one or more reflectors present inside and outside of the wellbore

Methodology Applied

Scientific EffectAcoustic wave transmission and reflection: Reflection

Implementation Method 2

processing the first and second ultrasonic waveforms using a deconvolution technique to generate an impulse response

Methodology Applied

Scientific EffectDeconvolution signal processing:

Data Source

PatentUS11598895B2Ultrasonic waveform processing using deconvolution in downhole environments

Publication Date: 2023.03.07 HALLIBURTON ENERGY SERVICES INC

AI summary

Deconvolution-based processing of ultrasonic waveforms enables robust calculation of two-way travel time for an ultrasonic caliper, particularly in the presence of multiple, proximal reflectors (e.g., mud cake, formation, casing, cement, etc.).